Consolidated Statements of Cash Flows (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net loss	$ (15,830,000)	$ (5,103,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	178,000	195,000
Non-cash derivatives (gain) loss	10,286,000	0
Common stock issued to 401(k) plan	53,000	41,000
Common stock issued for services		282,000
Share-based compensation expense	1,265,000	835,000
Changes in operating assets and liabilities:
Restricted cash	61,000	231,000
Prepaid expenses	529,000	(425,000)
Other assets	1,000	1,000
Accounts payable	224,000	(195,000)
Accrued expenses	320,000	(56,000)
Net cash used in operating activities	(2,913,000)	(4,194,000)
Cash flows from investing activities:
Purchases of property and equipment		(35,000)
Net cash used in investing activities		(35,000)
Cash flows from financing activities:
Proceeds from exercise of stock options	131,000
Repayment of note payable	(18,000)	(18,000)
Proceeds from exercise of warrants	2,819,000
Principal payments on capital lease obligation		(3,000)
Proceeds from issuance of common stock	11,038,000	116,000
Net cash provided by financing activities	13,970,000	95,000
Increase (decrease) in cash and cash equivalents	11,057,000	(4,134,000)
Cash and cash equivalents at beginning of period	13,459,000	13,980,000
Cash and cash equivalents at end of period	24,516,000	9,846,000
Supplemental disclosure of cash flow information and non-cash transactions:
Cash paid for interest	33,000	32,000
Reclassification of derivative warrant liability to additional paid-in capital	$ 4,866,000